A dynamical model of B-T cell regulation

We present a minimal regulatory model for the dynamics of the humoral immun e response of two lymphocytes populations (B and T helper) interacting with a specific antigen pool (bacterium). Stability analysis reveals that the s ystem accounts for the occurrence of multiple steady states in the absence as well as in the presence of the antigen population. The model exhibits (i ) a state of immune memory, (ii) one state with high antigen and low helper concentration (disease), and (iii) one state with low antigen and high hel per concentration (tolerance). The latter state allows oscillatory behavior . Injection of high antigen doses as well as minimal changes of structural parameters provoke the system to jump from the state of disease to the stat e of tolerance. This is reminiscent of therapies where the patient is treat ed with allergen, immuno-suppressants or drugs.